Area Forecast Discussion
Issued by NWS Central Illinois

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FXUS63 KILX 040843
AFDILX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LINCOLN IL
343 AM CDT MON MAY 4 2015

.SHORT TERM...(TODAY)
ISSUED AT 342 AM CDT MON MAY 4 2015

OUTFLOW BOUNDARY FROM CONVECTION THAT DEVELOPED AHEAD OF A FRONTAL
BOUNDARY EXTENDING THROUGH THE GREAT LAKES AND INTO THE CENTRAL
PLAINS HAS MOVED INTO PORTIONS OF THE CENTRAL IL FORECAST
AREA...EXTENDING FROM NEAR PEORIA TO PONTIAC. BOUNDARY CONTINUES TO
TRIGGER SCATTERED THUNDERSTORMS BEHIND IT...WHILE AHEAD LIGHT
SHOWERS ARE WIDELY SCATTERED ACROSS CENTRAL IL. MID-LEVEL
INSTABILITY ACROSS THE REGION WILL CAUSE SHOWERS AND THUNDERSTORMS
TO CONTINUE TO DEVELOP ACROSS MUCH OF CENTRAL IL MAINLY FROM I-70
NORTHWARD THROUGH MORNING. A POSSIBLE LULL IN PRECIPITATION
INDICATED BY MODEL FORECASTS LATE MORNING AS CURRENT AREA OF
CONVECTION SHIFTS NORTHEASTWARD AND RE-DEVELOPMENT OF CONVECTION
TAKES PLACE ALONG THE APPROACHING FRONTAL BOUNDARY FOR THE
AFTERNOON. SPC CONTINUES TO ADVERTISE A MARGINAL RISK FOR SEVERE
STORMS CONTAINING HAIL/STRONG WIND GUSTS THIS AFTERNOON/EVENING
THROUGH MUCH OF CENTRAL AND NORTHERN IL NEAR THE FRONTAL BOUNDARY
WHERE AT LEAST SOME OVERLAP OF MODERATE BULK SHEAR MAY COMBINE WITH
1000-2000 J CAPE. HIGH TEMPERATURES QUITE WARM AGAIN TODAY...UPPER
70S TO LOW 80S...WITH BREEZY SW WINDS 10-15 MPH.

&&

.LONG TERM...(TONIGHT THROUGH SUNDAY)
ISSUED AT 342 AM CDT MON MAY 4 2015

SOME CONVECTION SETTLING INTO THE MIDWEST THIS MORNING ALONG AND
AHEAD OF THE BOUNDARY JUST TO THE NORTHWEST. SAME BOUNDARY PROVIDING
THE FOCUS FOR SHOWERS TODAY WILL KEEP THE THREAT FOR SOME SHOWERS
AND THUNDERSTORMS THROUGH THE OVERNIGHT IN THE NORTHERN HALF OF THE
STATE.  EXACT LOCATION OF THE STALLED BOUNDARY VARIES A BIT FROM
MODEL TO MODEL.  SMALL WAVES MOVING ALONG THE BOUNDARY WILL KEEP
PRECIP CHANCES IN THE NORTHERN TIER OF THE STATE THROUGH TUESDAY.
HIGH PRESSURE SLOWLY BUILDING IN WITH SOME SOUTHERLY WINDS PUSHING
THE FRONT BACK TO THE NORTH AND OUT OF THE FORECAST AREA FOR TUESDAY
NIGHT THROUGH WED NIGHT. PRECIP CHANCES SLOWLY EDGING BACK INTO
CENTRAL ILLINOIS AS AN UPPER LEVEL WAVE PUSHES OUT OF THE SW.  THE
ENERGY IS PART OF A GENERAL PATTERN SHIFT TO MORE SOUTHWESTERLY FLOW
WITH THE UPPER LEVEL TROF DIGGING BACK IN OVER THE SWRN CONUS.  THE
SFC LOW WITH THAT STORM MOVES OUT INTO THE UPPER MIDWEST AND INTO
CANADA BY THE END OF THE WEEK, BUT IN SHIFTING TO MORE SOUTHWESTERLY
FLOW ALOFT, OPENS THE DOOR TO A SERIES OF SHORTWAVES THAT KEEP THE
FORECAST WET FOR THE END OF THE WORK WEEK AND INTO THE WEEKEND.
TEMPS RATHER WARM THROUGH THE FORECAST WITH OVERCAST AND RAINY SKIES
KEEPING THE OVERNIGHT LOWS UP A BIT, BUT LIKELY NOT NEARLY AS WARM
AS THE TREND IN THE GUIDANCE.  HAVE KNOCKED THEM DOWN A COUPLE
DEGREES. SOUTHERLY FLOW AND A RELATIVELY WARM AIRMASS KEEPING THE
HIGHS A BIT ABOVE NORMS.  HOWEVER, WITH THE LIFTING OF THE DEEP TROF
OVER THE SW INTO THE GREAT LAKES, THE WARMER AIRMASS IS SHUNTED OFF
TO THE EAST AND COOLER AIR MOVES INTO THE MIDWEST AT LEAST BRIEFLY
AT THE END OF THE FORECAST PD.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z MONDAY NIGHT)
ISSUED AT 1142 PM CDT SUN MAY 3 2015

WEAKENING LINE OF SHOWERS/STORMS APPROACHING CENTRAL ILLINOIS FROM
THE NORTHWEST LATE THIS EVENING. FURTHER WEAKENING IS ANTICIPATED
AND THEY MAY NOT REACH THE BULK OF THE LOCAL TERMINALS. KPIA AND
KBMI STAND THE BEST CHANCE OF SEEING STORMS. ADDITIONAL CONVECTION
OVER THE CENTRAL PLAINS IS MOVING MORE OF AN EASTERLY DIRECTION
AND THESE MAY IMPACT A PORTION OF THE REGION AS WELL VERY LATE
TONIGHT OR MONDAY MORNING. HOWEVER, IN BOTH CASES, COVERAGE BY THE
TIME THEY GET HERE IS NOT EXPECTED TO BE HIGH, SO HAVE GONE WITH A
VCSH/VCTS MENTION FOR NOW. ASIDE FROM ANY OF THIS CONVECTION,
EXPECT VFR CONDITIONS TO PREVAIL FOR MOST OF THE 06Z TAF VALID
TIME. EXPECT MOST OF THE ADDITIONAL DEVELOPMENT ON MONDAY TO STAY
MOSTLY TO THE NORTH OF THE AREA, ALONG A STALLED FRONTAL BOUNDARY,
ALTHOUGH KPIA AND KBMI STILL STAND THE BEST CHANCE OF BEING
IMPACTED.


&&

.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

$$

SHORT TERM...ONTON
LONG TERM...HJS
AVIATION...BAK



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